Transgender Identity and Suicide Attempts and Mortality in Denmark.

Importance: Prior studies have suggested that transgender individuals may be a high-risk group with respect to suicide attempt and mortality, but large-scale, population-based investigations are lacking. Objective: To examine in a national setting whether transgender individuals have higher rates of suicide attempt and mortality than nontransgender individuals. Design, Setting, and Participants: Nationwide, register-based, retrospective cohort study on all 6 657 456 Danish-born individuals aged 15 years or older who lived in Denmark between January 1, 1980, and December 31, 2021. Exposure: Transgender identity was determined through national hospital records and administrative records of legal change of gender. Main Outcomes and Measures: Suicide attempts, suicide deaths, nonsuicidal deaths, and deaths by any cause during 1980 through 2021 were identified in national hospitalization and causes of death registers. Adjusted incidence rate ratios (aIRRs) with 95% CIs controlling for calendar period, sex assigned at birth, and age were calculated. Results: The 6 657 456 study participants (50.0% assigned male sex at birth) were followed up during 171 023 873 person-years. Overall, 3759 individuals (0.06%; 52.5% assigned male sex at birth) were identified as transgender at a median age of 22 years (IQR, 18-31 years) and followed up during 21 404 person-years, during which 92 suicide attempts, 12 suicides, and 245 suicide-unrelated deaths occurred. Standardized suicide attempt rates per 100 000 person-years were 498 for transgender vs 71 for nontransgender individuals (aIRR, 7.7; 95% CI, 5.9-10.2). Standardized suicide mortality rates per 100 000 person-years were 75 for transgender vs 21 for nontransgender individuals (aIRR, 3.5; 95% CI, 2.0-6.3). Standardized suicide-unrelated mortality rates per 100 000 person-years were 2380 for transgender vs 1310 for nontransgender individuals (aIRR, 1.9; 95% CI, 1.6-2.2), and standardized all-cause mortality rates per 100 000 person-years were 2559 for transgender vs 1331 for nontransgender individuals (aIRR, 2.0; 95% CI, 1.7-2.4). Despite declining rates of suicide attempts and mortality during the 42 years covered, aIRRs remained significantly elevated in recent calendar periods up to and including 2021 for suicide attempts (aIRR, 6.6; 95% CI, 4.5-9.5), suicide mortality (aIRR, 2.8; 95% CI, 1.3-5.9), suicide-unrelated mortality (aIRR, 1.7; 95% CI, 1.5-2.1), and all-cause mortality (aIRR, 1.7; 95% CI, 1.4-2.1). Conclusions and Relevance: In this Danish population-based, retrospective cohort study, results suggest that transgender individuals had significantly higher rates of suicide attempt, suicide mortality, suicide-unrelated mortality, and all-cause mortality compared with the nontransgender population.